KT has applied technology to allow extended use of smartphone batteries during voice calls for the nationwide LTE network for the first time here, the company said Monday.

This is an expansion of connected mode discontinuous reception, or C-DRX, technology, used for internet data to be applied to voice calls. KT first adopted C-DRX for data in the LTE network early last year.

When a user is receiving and sending data through the LTE network, data is not sent continuously but in intervals. C-DRX reduces energy use during data reception by switching to low-power mode in the gaps between the intervals, extending battery life. 

According to KT, C-DRX is more difficult to apply to voice calls vis-a-vis regular data because the gaps in the intervals are shorter. In voice calls using LTE, voice data is sent every 20 milliseconds. KT has applied C-DRX tech to those short intervals to extend battery life during voice calls.

A test of the technology using the iPhone X by the Telecommunications Technology Association showed that C-DRX could extend battery life during voice calls by up to 51 percent.

During the test, a fully charged iPhone X with C-DRX off showed a maximum of 12 hours and 46 minutes of voice calling time. With C-DRX turned on, the same model was able to support up to 17 hours and 24 minutes of voice calling.

The technology will be automatically applied for LTE users subscribing with KT. 

By Won Ho-jung (hjwon@heraldcorp.com)